The present invention relates to systems for the transmission of information, and especially to such systems for transmitting information in serial digital form.
There are a variety of instances in which information available in parallel form is to be transmitted through a common channel in serial digital form. Such a serial signal may be generated by a parallel-to-serial converter which sequentially and repetitively addresses or samples a set of parallel signals to derive successive pulses having values corresponding to the corresponding contemporaneous values of the several parallel signals. At the other end of the channel, the samples may be passed through a serial-to-parallel demultiplexer which reconstitutes the original parallel signals from the transmitted samples. In an especially important form of such systems the parallel signals are binary digital signals having at various times either one or two values or levels, commonly designated as a 0 or a 1.
It is usual in such apparatus to sample all of the parallel signals periodically and at the same rate, sufficiently often that no significant changes occur in any of the parallel signals which are not detected and represented by the samples. In such usual types of system then, each parallel signal is sampled at intervals no greater than the shortest time duration of significant changes in any of the parallel signals. This requirement for sampling all of the signals at a specified minimum rate requires a corresponding minimum bandwidth for the transmission channel, in order to assure accurate and reliable signal transmission over substantial distances. The greater the required bandwidth, the shorter and/or more expensive is the transmission channel which will transmit the signals accurately and reliably.
It is an object of this invention to provide a new and useful system and method for transmitting information, particularly binary digital information.
Another object is to provide such system and method which are conservative of the channel bandwidth required to transmit the signals accurately and reliably.
A further object is to provide such system and method which, at least for parallel signals having certain characteristics, accomplishes parallel-to-serial conversion, transmission of the serial signals, and reconstitution of the transmitted serial signals into parallel signals, with a required bandwidth smaller than is necessary in conventional systems.